Anti-cytokine receptor drugs have had a tremendous clinical impact on autoimmune disease, as evidenced by the effectiveness of IL-1β and TNFα blockade for rheumatoid arthritis and psoriasis. However, since not all patients respond to these treatments, new strategies are still needed. A fundamental understanding of receptor structure and subunit interactions is a key for developing novel therapeutics. In this regard, IL-17 and the closely related cytokine IL-17F are the defining cytokines of a newly-described subset of Th cells termed “Th17.” Th17 cells and IL-17 have both been implicated as causative factors for many autoimmune diseases, including rheumatoid arthritis (RA), colitis and multiple sclerosis/experimental autoimmune encephalomyelitis. The first known IL-17 binding protein, IL17RA, is the founder of a unique receptor superfamily, and there is considerable interest in targeting IL-17 or its receptor as anti-cytokine therapeutics. However, the composition, subunit dynamics and ligand binding contact sites of the IL-17 binding complex are poorly defined. It was previously demonstrated that an IL-17 binding complex contains at least two subunits of IL-17RA, which are pre-assembled in the cell membrane prior to contact with ligand (either IL-17 or IL-17F). The region within IL-17RA that mediates receptor multimerization is unknown. Thus, there is a need to characterize this receptor at a molecular level and to develop methods and compositions for targeting it and/or IL-17.